The present invention relates to actuators that operate operative units such as clutches and, more particularly, to an actuator having a cam converting mechanism or a gear converting mechanism using an electric motor as a drive power source.
FIG. 1 shows a differential unit 2001 disclosed in Japanese Patent Application Publication No. 5-54574. This differential unit 2001 has a drive power connecting and disconnecting mechanism mounted at an input side of a differential mechanism.
The differential unit 2001 is accommodated in a differential carrier 2003. And, the differential unit 2001 is comprised of an outer differential case 2005, an inner differential case 2007, a differential mechanism 2009 having a bevel gear, a meshing clutch 2011 and an actuator 2013 using a fluid pressure.
The meshing clutch 2011 is disposed between a clutch ring 2015 connected to the inner differential case 2007 for free movements and the outer differential case 2005.
The actuator 2013 is comprised of a cylinder 2017 fixedly secured to the differential carrier 2003, a piston 2019, and a shift fork 2021. The actuator 2013 is supplied with air pressure from an air pump driven by an engine and operates in response thereto. And, the actuator 2013 operatively moves the clutch ring 2015 through the shift fork 2021, thereby causing the meshing clutch 2011 to be brought into meshing engagement. Also, when interrupting supply of air pressure, the meshing clutch 2011 is brought out of meshing engagement.
The outer differential case 2005 is rotationally driven by a drive power of the engine inputted through a drive pinion gear 2023 and a ring gear 2025.
Upon meshing engagement of the meshing clutch 2011, rotation of the outer differential case 2005 is distributed to left and right wheels through wheel axles 2027, 2029 by means of an inner differential case 2007 and the differential mechanism. This results in a vehicle being brought into a four-wheel drive condition, with resultant improvement in a rough-road running capability, a rough-road escaping capability and a stability.
Upon meshing disengagement of the meshing clutch 2011, further, the drive power of the engine in a drive power transmission system between the inner differential case 2007 and the left and right wheels is disconnected. As a result, the vehicle is brought into a two-wheel drive condition, improving fuel consumption.